1. Field of the Invention
The present invention relates to an anti-bacterial, anti-fungal and anti-viral composition with excellent sterilizing power, deodorization and adhesion activity, an application thereof, and a method for preparing the same. More particularly, the present invention relates to a composition with sterilizing activity against bacteria, fungi and viruses, comprising silver colloid, titanium dioxide nanoparticles, a dispersion stabilizer, a binder and water, an application thereof, and a method for the preparation thereof.
2. Description of the Related Art
Silver has long been known to show anti-bacterial activity. Particularly, silver colloid, that is, silver clusters (10 to 150 nm in size) evenly dispersed throughout an aqueous solvent, are found to have potently sterilizing activity against approximately 650 species of harmful bacteria and fungi. In addition, it has been observed that when colloidal silver particles are applied to the body that they do not kill most beneficial bacteria.
Further, silver colloid solutions are recognized as a natural substance that has been approved for medical use by the FDA. Recently, colloidal silver has been used as a preservative in foods with the official permission of the FDA. Therefore, colloidal silver is regarded as being non-toxic to the body.
As silver colloid solutions are verified to have potently antibacterial activity while being non-toxic to the body, active studies have been performed to develop silver particles having more effective antibacterial activity, colloidal silver agents for killing pathogenic bacteria and treating diseases, and the use thereof in various products including cosmetics, fibers, wallpaper, washing machines, clothes, etc.
When exposed to light of the proper energy, a photocatalyst shows electrically semiconductive properties, generating active oxygen species or hydroxyl (OH) radicals which induce strong redox reactions responsible for antibacterial activity and the degradation of stinking materials. A certain level of energy causes electrons in a semiconductor to be excited from the valence band to the conduction band. While electrons (e−) are excited to the conduction band, holes (h+) are created in the valance band. These electrons and holes perform various reactions including the degradation of harmful materials by means of potent oxidation or reduction.
Titanium dioxide (TiO2) is representative of photocatalytic oxides and finds the broadest applications in the photocatalytic fields thanks to its chemical stability and excellent semiconductor properties. Titanium dioxide can sufficiently perform photocatalytic activity when an energy of 3.0 eV (a bandgap between the valence band and the conduction band, corresponding to light with a wavelength of 380 nm) is applied thereto.
The electrons (e−) and holes (h+) generated upon the exposure of the photocatalyst titanium dioxide to light respectively react with O2 and H2O in air to produce the two active oxygen species of a superoxide anion (O2−) and a hydroxy radical (.OH) on the surface of the titanium oxide. Having redox potential, the hydroxyl radical is able to oxidize most materials whereby it is effectively used to purify NOx, volatile organic compounds (VOCs) and various stingy odors, to remove BOD, chromacity, degradation-refractory contaminants and environmental hormones of livestock wastewater, domestic sewage and industrial wastewater, and to kill various pathogens and bacteria such as pathogenic Escherichia coli, Staphylococcus aureus, O-157, etc., with an efficiency of 99% or higher.
Titanium dioxide is economically beneficial because its redox reaction can be elicited by fluorescence light as well as solar light and its performance is semi-permanent through the cycle of “settlement on substance→photolysis→regeneration.” In addition, titanium dioxide functions as a photocatalyst in various applications, with the concomitant production of non-toxic materials such as water and CO2.
According to the WHO, SARS (Severe Acute Respiratory Syndrome) is caused by the SARS coronavirus, a variant of the coronavirus causing colds in human. A coronavirus is a kind of RNA virus with a high mutation rate. Further, coronaviruses exhibit high recombination frequency because the synthesis of the RNA viral genome is discontinuous due to template switching.
Coronaviruses infect humans, causing mainly respiratory symptoms such as a cold in the nose. Generally, an infection by the coronavirus has not been regarded as a significant problem because there was only a low risk of infection before the outbreak of SARS. However, they often act as fatal pathogens in some animals such as cow, dogs, pigs, birds, etc., and experts had expected that when mutated in livestock such as pigs, chickens, etc., coronaviruses can cause a fatal disease in the human body. SARS spreads by means of infection via aerogenous droplets, e.g., spit droplets from SARS patients or by contagion via materials (e.g., doorknobs, telephones, keyboards, etc.) contacted by SARS patients.
Human influenza (HI), used to refer to epidemic influenza cases which were caused by influenza virus endemic to human populations and are generally generated at the turning of the seasons and in the winter (e.g., from November to March), can spread rapidly due to the severity of its symptoms and its high infectious potential. Human flu-causing viruses can belong to any of three major influenza-causing Orthomyxoviruses—Influenza A virus, Influenza B virus and Influenza C virus, which are single-stranded RNA viruses.
Particularly, the influenza A virus experiences frequent nuclear rearrangement, causing pandemic flu while the influenza C virus is responsible for respiratory diseases that are not serious.
Avian influenza is an influenza caused by viruses adapted to birds such as poultry or wild birds. As a rule, influenza viruses are classified into A, B and C viruses. Of these, the influenza A and B viruses are known to infect the human body, with a pandemic flu being caused only by the influenza A virus.
On the surface of an influenza virus, there are projections consisting of specific hemagglutinin (HA) and neuraminidase (NA). Because there are 16 different hemagglutinins and 9 different neuraminidases, 166 (=16×9) types of influenza viruses can theoretically exist. Of them, three distinct HAs (H1, H2 and H3) and two different NAs (N1 and N2) are found in human infections while avian influenza infections are associated mainly with the H5 or H7 type.
Among them, H5N1 virus is known as a highly pathogenic influenza virus causing flu in bird and poultry populations. Avian influenza spreads from one bird to another via nose drippings, respiratory secretions, and feces. In most cases, feces carry the avian influenza virus to the mouth. Thus, for example, instruments, feedstock, bird cages, clothes, etc., when contaminated with respiratory secretions or feces of birds, are the main mediators of bird flu.
Since the first report on the outbreak thereof in Mexico and the United States in April, 2009, the so-called new flu, caused by influenza A virus subtype H1N1, also known now as the new H1N1 virus, has spread worldwide.
Until seven days after the appearance of symptoms, the patients infected with the new influenza A virus subtype H1N1 can transmit the virus to healthy persons. The transmittable period of time may be longer for children. Above all, it is important to wash the hands in order to prevent infection with the new influenza A virus. It is recommended to wash the hands frequently and to avoid touching the eyes, the nose and the mouth with the hands because the virus may be on door knobs, public telephones, etc.
Inhibitors against coronaviruses and influenza viruses, and silver- or titanium dioxide photocatalyst-induced sterilization have been described previously.
Products with sterilizing activity against coronaviruses are made mostly from extracts of synthetic organic materials or natural materials (see, for example, Korean Patent Laid-Open Publication No. 2003-0063961 and Japanese Patent Laid-Open Publication No. 2000-44473), which are not inorganic solutions.
Colloidal silver or titanium dioxide is used as an inorganic antibacterial agent. There are various applications using such inorganic antibacterial agent, including silver-coated clothes, antibacterial sprayers (Korean Patent Laid-Open Publication No. 2002-0008375), coating agents for air filters, and the like. Products with silver show almost no changes in performance irrespective of environmental conditions whereas products based on the photocatalyst have insufficient performance under low intensity radiation.
Products using both silver and titanium dioxide and preparation methods thereof are disclosed in Korean Patent Laid-Open Publication Nos. 1998-0007982 (Method for Preparing Inorganic Anti-Bacterial Agent), 2001-0057595 (Method for Preparing Silver-Coated Photocatalyst) and 2003-0037050 (Titanium Dioxide Photocatalyst Containing Anti-Bacterial Metallic Ingredient and Preparation Method thereof).
In Korean Patent Laid-Open Publication No. 2003-0037050, antibacterial metals such as silver is formed into a colloid which is then mixed with titanium dioxide and fabricated into crystalline oxides through hydrothermal synthesis. The crystalline oxides are coated using a sol-gel method and microcapsulated to afford photocatalytic material containing antibacterial metal. Korean Patent Laid-Open Publication No. 1998-0007982 contemplates a silver ion-impregnated inorganic antibacterial agent which is prepared by mixing phosphoric acid, silver nitrate, titanium dioxide powder and colloidal silica, and sintering the mixture. Contemplated by Korean Patent Laid-Open Publication No. 2001-0057595 is a method for preparing microparticular photocatalyst in which photocatalytic powder is coated with silver by intermetallic substitution.
The composition and the synthesis method thereof contemplated by the present invention are constitutionally different from the prior art products and synthesis methods using silver and titanium dioxide.
To overcome the problems encountered in the prior art, the present inventors process the two nanoparticles of colloidal silver and titanium dioxide, both of which exhibit anti-bacterial, anti-fungal and anti-viral activity, in such a simple manner that titanium dioxide is combined with colloidal silver homogeneously dispersed in solvent using a binder, instead of using the complicate processes of mixing, hydrothermal synthesis of a complex, intermetallic substitution, and sintering. The present invention is the result of overcoming such problems with the prior art.
In addition to the simplicity of synthesis, the present invention enjoys the combined effect sterilizing activity against bacteria, fungi and viruses of both silver and titanium dioxide. The inorganic solution comprising colloidal silver and titanium dioxide particles maintains potently antibacterial, antifungal and antiviral activity in the presence or absence of light.
The solution according to the present invention is effective for inhibiting a broad spectrum of viruses, bacteria and fungi and removing stingy odors. Particularly, the composition of the present invention has potently sterilizing activity against SARS coronavirus (TGEV, PEDV), avian influenza (AI) virus, swine influenza (SI) virus, human influenza (HI) virus, hand, foot and mouth disease virus, and new super bacteria (NDB-1) at a killing rate of 99.9% or higher.
Further, the composition of the present invention is highly adhesive so that a material of interest can retain potently anti-bacterial, anti-fungal and anti-viral activity for a long period of time after being applied with the composition.
Moreover, the composition of the present invention can decompose formaldehyde and ammonia, which cause sick house syndrome.